Tools for certain operations require a fairly high degree of precision. Illustratively, some operations require precise torque values to be applied to fasteners. One of the most effective ways to accomplish this goal is to provide a self-limiting torque wrench having a mechanism for limiting maximum applied torque. With such a mechanism, a user can freely turn the wrench without having to pay attention to the amount of torque being developed. Free turning of the wrench may entail alternating direction of wrench rotation, since that can be performed conveniently with one hand, without requiring that the hand be removed from the tool.
In some usages and environments, such a torque wrench can develop serious deficiencies. For example, in the field of high precision assembly, a torque wrench may go out of calibration to a degree unacceptable to assembly or fabrication standards. In another example, a torque wrench used in medical procedures such as installation of inserts in the human body may become internally contaminated, or may start to leak lubricant.
There exists a need for a torque wrench which overcomes the problems facing manually used wrenches.